In recent years, as a method for forming solder resist layers on printed-wiring boards for consumer use and industrial use, a method using a liquid solder resist composition that has excellent resolution, size precision, and the like, and can be developed has been widely adopted, instead of a screen printing method, in order to increase the density of wiring on the printed-wiring board.
Also, in recent years, optical elements such as light-emitting diodes are often mounted directly on a printed-wiring board on which a solder resist layer is formed to cover the printed-wiring board, for uses in: backlights of liquid crystal displays of mobile terminals, personal computers, televisions, and the like; light sources of illumination devices; and the like. Furthermore, as a result of the solder resist layer of the printed-wiring board on which optical elements are mounted containing titanium dioxide, the solder resist layer is whitened, which allows light emitted from light-emitting elements to efficiently reflect off the solder resist layer (see JP2011-17010A, JP4657358B, JP2011-215384A).